Jolting and squeeze control for molding machines



Dec. 14, 1937. w. H. NICI-IOLLS ET AL 2,102,377

JOLTING AND SQUEEZE CONTROL FOR MOLDING MACHINES Filed No'v. 22, 1935 2 Sheets-Sheet 1 Dec. 14, 1937. w. H. NICHOLLS El" AL 2,102,377

JOLTING AND SQUEEZE CONTROL FOR MOLDING MACHINES Filed Nov. 22, 1935 Sheets-Sheet 2 Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE JOLTING AND SQUEEZE CONTROL FOR MOLDING.- MACHINES Application November 22, 1935, Serial No. 51,144

8 Claims. (01. 22-45) The invention relates to molding machines of the type provided with fluid pressure operated jolting, squeezing and pattern drawing means.

More particularly, the invention has special reference to the variety of molding machines disclosed in Patent No. 1,676,662 granted to W. H. Nicholls July th, 1928 which in turn is an improvement over the machine forming the basis of an earlier prior Patent No. 1,472,807 to W. H. Nicholls dated November 6th, 1923. In this type of device there is provided a manually controlled fluid pressure operated mechanism for imparting a series of jolts to the mold flask for packing the sand therein, closely around the pattern. There is also provided a similarly operated squeeze means for applying a heavy pressure to the mold flask for compacting or densifying the sand therein in order to improve the quality of the molds. Moreover, the squeeze mechanism acts, when fluid pressure thereon is relieved, to draw the patterns from the mold. In the use of such machines it has been the practice to leave to the operators judgment the question of the number of jolts to be applied and in some instances it may frequently occur that, through haste or carelessness, an insufiicient number of jolts may be given the flask. Then again if the operator is in a hurry it is easily possible for him to release the fluid pressure operated squeeze means before the pressure therein has built up to the maximum. Either of these contingencies will naturally result in producing molds which are not uniform in density or compactness and this is naturally a serious drawback.

It is with the above facts and conditions in view that we have devised the present invention which has for its principal object the provision of a control means which may be set in advance and which will automatically govern the number of jolts applied to the flask so that as long as the initial setting remains the same all the molds of a series will be subjected to the same jolting action instead of this being left to the discretion or care of the operator.

A more specific object of the invention is to provide an automatic jolt control comprising a fluid pressure operated hydraulic type of valve for timing the duration of the supply of fluid pressure to the jolting mechanism, an adjustment being moreover provided whereby the time element may be regulated for varying the number of jolts applied to the flask.

Another important object of the invention is to provide an automatic means for preventing the release of the fluid pressure in the squeeze mechanism until the pressure therein has built up to the maximum whereupon a retaining latch on the control valve is released enabling the valve to be moved to neutral position, thereby insuring the application of the same squeeze pressure to all of the flasks in a series.

An additional object is to provide the above mentioned automatic control means which is well adapted to be built into and to form a part of molding machines embodying the same general principles as disclosed in said prior patents above referred to though it is to be understood that this is not limitative as the same mechanism can be applied to other molding machines incorporating fluid pressure jolt and squeeze means, it being moreover a feature that this automatic control could be installed as an adjunct to already existing machines without difficulty particularly as our control devices are simple and inexpensive to make and apply.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawings in which:

Figure 1 is a view mostly in Vertical section through a molding machine of the type shown in said prior Patent No. 1,676,662, certain parts being broken away, and the automatic control means being shown in side elevation,

Figure 2 is a view partly in elevation and partly in section showing the manual control valve, and looking at it in the direction of the arrow A in Figure 1,

Figure 3 is a cross section therethrough taken on the line 33 of Figure 2,

Figure 4 is a fragmentary elevation of the manual valve with the automatic squeeze control means shown in section, the view being taken on the line 4-4 of Figure 5, with the valve body in section,

Figure 5 is a plan view of the manual valve,

Figure 6 is a vertical section through the automatic timing or jolt control valve,

Figure 7 is a plan View thereof.

Though said prior Patent No. 1,676,662 speaks for itself, yet, for the sake of clearness, following is a description of the general construction in order to explain more fully the functions and advantages of the automatic control 'means forming the subject matter of the present invention.

Referring more particularly to the drawings, the numeral l designates the base of the machine which is formed at its upper; end with a relatively large vertical cylinder 2 open at its .upper end and closed at its lower end by a horizontal wall 3; Formed integrally with the cylinder 2 and base I are laterally extending horizontal arms [and 5,

the latter being shown as broken away inasmuch as it is a duplicate of the former.

The arm 4 carries an upstanding post 6 which serves as -'a support for a pressure head, not shown in the present instance. In the cylinder 2-is:fitted. a large squeeze piston I closed at its lowerend and openat its upper end. This squeeze pistonis movable withinthe cylinder 2 in a vertical direction and its'upward movement is limited as by a headed bolt 8 rigidly mounted in the bottom wall 3 of the cylinder and extending through a hole in the bottom wall of the piston. Toprevent leakage the squeeze piston is provided with a v packing ring 9 located near its lower end and bearing against the inner wall of the cylinder '2.

Formed integrally at the center of' the bottom wall of thesqueeze piston 1 is a relatively small vertically arranged cylinder in which extends the entire height of the squeeze piston 1. The upper end of the small cylinder I0 is open and its lower end is closed by the bottom wall ll. of the squeeze piston and a short distance above its bottom this cylinder) is formed with an exhaust interior of the surrounding portion of the squeeze piston and thence with the atmosphere. f ittingwithin the cylinder M is a hollow,-cylindrical'jolt: plunger 13 whichis vertically. elongated, its length. being greater than the height of the cylinder. Ill.

port .I 2, of liberal size, which places the lower portion of the cylinder I0 in communication with the Adjacent its lower end the plunger is formed with inner surface of the cylinder lflto form a fluid proof joint. Formed integrally. with the upper' a transverse. wall 14, the cylindrical wall of the plunger extending below said transverse wall in .the 1 form of an annular 'skirt or flange {5 which is provided near its lower end with a packing ring l6 bearing against the end of the jolt piston is a jolt and squeeze' head I? the lateral arm 5, broken away in the. drawthereof which'rests upon the upper end of and closes the squeeze piston and which'alsoclosesfthe upper 1 end of the jolt piston except for a central threaded- 1 opening l8 which is closed by a plug [9 screwed 'thereinto. f

The piston isformed adjacent its upperiend with a charging port 200i generous size and has its cross wall-l4 formed with a'port. 2| of much less size than the ports 12 and 20. The plunger,

with its .end' walls, 'define's an 'air reservoir 22 which .extends'throughout the greater portion of the length of the' plunger andtherefore has considerable volume. 'Thisreservoir is:closed except 7 for the ports 20- and 2-'l. "Ih e portll admitsiair" from the reserVoirZZ intothefexpansion space at the lower end of jthe cylinder. 10, below the plungerpand said port' will be referredEto as the admission port. Thecross'wall 14 of the plunger and the skirt or flange below the same 'wmirorm 1 ype '1 though.

or disk 21 having two arcuate concentric passages 28 and 29 in its undersurface. The base-is formed with a supply port 30 connected to an air supply by means of apipe 33. A pipe 34 connects the lower end; of the squeeze cylinder -2.;with a squeeze supplyport 32iwhile connected with a port 36 is a pipe 31 for supplying air pressure to the'port 20 of the jolting piston, there being, how-.,

ever, interposed the automatically hydraulically.

."acting.jolting-control' valve indicated as a whole by the'numeral 38 and which will'be hereinafter V The rotary valve 21 is connected to a stem 39 by 'any suitable means and said stem is provided more. fully. described. The numeral 35 desig-I 'nates an exhaust port which may have connected therewith a small manual valve 3| which can be set to regulate the rate of exhaust.

at its upper end with an operating handle 40.

By rotating the valve to the desired position, air

or other fluid under pressuremay be admitted to operate the jolt piston or thesqueeze piston or V to exhaust the .air from. beneath the squeeze piston. In the'position shown in Figure 3 theports are arranged to admit air fromthe'supply port 3.0,. passage 29,,port 35'and pipe -3T to the 25 1 automatic control valve 38 and; thence to the jolt' piston, this figure showing the squeeze piston cylj inderas open to the atmosphere through the ex-.

. haust port 35. .A partial rotation of. the valve clockwise will connectthe 'airisupplyirom the port3il through the passage 28 and'port32 .to the squeeze .piston. Afterthesqueeze. operation, partial rotation of. the'valve. counterclockwise will bring it to its-neutral position andccnnect the squeeze piston and port 32 throughthe passage 28fto the exhaust port 35 the supply and jolt piston ports being closed. a

; The respect in which the valve 23 difiers'from what -.is disclosed in said prior Patent No.

1,472,807 is the provision on the valve '23 of automatically acting means' to prevent the exhausting 'ofg'the air frombeneath the squeeze piston before the pressure has reached the maximum. To accomplish this there is providedon the handle '40 a-hollow extension formed as a. casing have ing. achamber .42 therein and containing avertically "slidable latch plunger. 43. onsthe intermediate portion of which is secured apistonj located within the chamber 42 and urged downwardly by a coil springISsurrQun-ding the upper-'1 p'o'rtion'of the, latch plunger and abutting within 1 .a chambered" plug 46 which is threadedly ad-.

justably connected with 'a bushing 4T-screwed: j into and closing thetop of the chamber 42. The

plug lfi'has an outlet 48,,to theatmosphere' to prevent compression of airin'the chamber above the 'piston 44; When the handlei lll -.is "moved. into the squeeze position the latch plunger )43 will ride up over the inclined surface M! andg catch behind the vertical shoulder 55 .of a keeper:

5| formed or secured upon the upper'portion'oif the valve' casing' 25. The spring tension urging. V

. the. plunger 43 downwardly may be regulatedby- After the ;valve is thus; a latched it cannot be moved "manually. To effect release we provide a pipe52 communicatingwith' the lower end of thechamber '4 2 and connected rotating the plug 46.

with a port 53 at the bottom of the squeeze cylin- .der "2;. Itwill beseen that after the valve has been latched it will remain sountil'the' air pressurein the squeeze' cylin'der builds upto the maximum whereupon this 'pressure' passing through the pipe52 into the chamber will lift" therpiston 46 againstthe resistance'of thespring ii-and retract the latchplunger 43 out"of 'cngagement with the keeper i whereupon the valve handle may be turned to the proper position for exhausting the air from the squeeze cylinder.

The jolt and squeeze head ll is formed with laterally extending arms 5%, one of which is here represented as broken away, and these arms carry vertically extending tubular sockets 55 at their outer ends. Secured upon the head is a pattern plate supporting frame 56 and upon this is secured the pattern plate 5'! over which is placed the mold flask E8. Surrounding the frame 55 is a substantially rectangular flask supporting frame 59 upon which the marginal front and rear edges of the flask are adapted to rest. The frame 59 is provided at its corners with depending guide pins which slidably fit within the sockets 55. The ends of the frame are provided centrally with depending plunger rods M which are slidably fitted Within sockets 62 carried by the ends the arms 4- and 5. Within the sockets the rods are adapted to be engaged by lock-up means, shown, to hold the frame 59 and the flask in an elevated position after the squeezing operation. The jolt and squeeze head 5? is not locked up but is free to return after a squeezing operation and to carry the pattern plate down with it. The patterns are thus drawn. from the mold.

The automatic control valve which is indicated as a whole at Figure l and which provided for the purpose of regulating the number or" jolts to applied to the molding flask is illustrated in detail in Figure 5 wherein it is shown in closed position. This valve mechanism comprises a casing or body formed with a bore and a chamber or reservoir 4'55, the latter having a filling opening il normally closed by a plug 68 vented at 5G to prevent the development of pressure. This chamber or reservoir also has a clean-out opening normally closed by a plug "lb. The casing it. lf may have any preferred means whereby it may be mounted upon the molding machine, as for example it may be provided with lateral ears H wh ch provide accommodation for securing bolts.

The lower or" the bore 55 is closed by a screw plug 72 ough which extends a nipple 13 connected with the compressed air conducting pipe 37 which leads from the manual control valve The intermediate portion of the easing or body E5 is formed with an outlet port 14 with which is connected a pipe '55 leading to the port 29 of the jolting cylinder. Slidable axially within the bore 55 is avalve device including a stem '56 provided at its lower end with a valve head i! which rests of the plug '52 as shown dot and lines when this automatic valve is open but which obstructs the outlet port for cutting flow of compressed air to the jolting cylinder when the automatic valve is closed. This valve head H is formed with passages lil which permit compressed air to pass above the head. At its intermediate portion the stem it is equipped with a suitably packed piston i9 urged downwardly by a coil spring ill] within the confines of which is a nut Bl. screwed onto a threaded portion of the stem 5 for holding the piston assembled in proper position in abutting engagement with a flange or collar 32 on the stem.

The upper end of the bore 65 is closed by a screw plug 83 through which extends an exteriorly threaded sleeve 84 carrying, at its lower end, an abutment 85 engageable by the nut 8| for the purpose of limiting the upward movement of the piston l9 and hence the stem 16 and valve head 77. The space above the abutment 85 constitutes an oil chamber 86 which communicates with the reservoir through a port 81 and which also communicates with the interior of the sleeve 34 through ports 88. The space between the piston 79 and the abutment 85 likewise constitutes an oil chamber 89 which communicates with the reservoir 56 through a port 963 and a passage 9d, the latter being normally closed by an upwardly unseating ball check valve 92. In order that oil may be enabled to pass, under proper conditions of operation, from the chamber 89 into the chamber 86 and thence into the reservoir E56, the upper end of the stem 15, where it is adapted to enter the sleeve 84, may be slightly reduced in size or may have longitudinal grooves to provide a slight clearance space 93 between its periphery and the interior of the sleeve.

In the operation of the machine, after the flask has been placed in position over the pattern plate and filled with sand, the valve 23 is manipulated to direct air under high pessure through the pipe 37 into the automatic jolt timing valve 38 and thence through the charging port 2%! of the plunger reservoir 22. Air entering the valve 38 through the pipe 31 passes through the nipple l3 and enters the lower portion of the bore 65. Normally the piston 79, stem '56 and valve head 'i'l' are at the lower limit of their movement. Air entering the lower portion of the bore 55 passes through the passages 78 in the valve head 17 and flows through the outlet pipe E5 to the jolting reservoir. When air enters this reservoir 22 it passes through the admission port 2! into the cylinder space below the plunger. The plunger is forced upwardly a short distance, carrying with it the head ll, the frame 59, the pattern plate 5'! and the flask. A short upward movement of the plunger causes the flange 55 to uncover the exhaust port E2 to vent the cylinder ill to the atmosphere and permit the plunger and the various parts which it supports to drop back until the head ll strikes the upper end of the squeeze piston I. The port l2 then becomes covered whereupon air pressure in the reservoir 22 will again pass through the port 2| and build up beneath the transverse wall !4 so that the plunger 22 will again be forced upwardly for another jolt. These jolt movements continue in rapid succession as long as air under pressure is permitted, by the automatic valve 38, to enter the plunger reservoir 22. By the provision of the relatively large air reservoir 22 closely adjacent to the expansion space below the plunger, a very rapid jolt operation is effected. It has been found desirable in practice to reduce the extent of the flask lift and to cause the jolts to occur with great frequency. The present arrangement accomplishes this. The volume of space below the plunger is small in comparison with the volume of the reservoir 22 even in the elevated position of the plunger. It is obvious, therefore, that in equalizing with the small expansion space the pressure in the reservoir 22 is reduced only slightly. A large volume of air at high pressure is therefore constantly maintained during the jolting operation almost at the immediate point where it is needed. The admission port 2! is made much smaller than the exhaust port I2 in order that very little air shall be lost when the cylinder space below the plunger is' vented to the atmosphere.

Injprio-r constructions, even in said former Patent No.'1,676,662 ,the number of jolts applied to the flask was a matter which was not definitely controlled in that reliance was placed simply 7 'upon the operator and undersuch circumstances it naturally occurs that a seriesof molds would not necessaril'y be subjected to the same number' of jolts, this 'resultingiin lack 'of uniformityin the molds. However, with the automa tic valve 38interposed in the compressed air supply line from the manual valve 23'to the plunger reservoir 22, .the'number of jolts is governed automatically. The manner in which this is accomplished is that when the manual valve is opened' for supplying'air to the valve "38 and thence out through the port 14 and pipe 15 to the plunger reservoir, a portion of the: air passing through'the-passages l8 in thevalve head 11 'causes pressure to build up beneath the piston 19 whichis then urged upwardly" against the,

resistance of thespring 83. This causesggpressure to be appliedby the piston to theoil within the chamber 89 and this'oil is slowlyforcedout through the space 93 ,into the sleeve '84 from which it passes through the. parts 88' into the chamber 36 from which it flows through the port 81 into the reservoir lifi. 'When the stem 76 and piston 19 have reached the upper limit of 7 their movemenfi with the nut 8 l -engaging against the abutment as a stop, the valve'hea'd 'l'l is' in obstructing rela'tion to the outle't port Misc 7 the compressed airjis supplied to the plunger that'flow of compressed air to the jolting plunger "isicut off. a An appreciable time is required for the oil to passup through the small space '93 and as a consequence-the time interval during which reservoir 22 will be considerablesothat a series of jolts will be applied to the flask. By screw ing the sleeve 84 in or out and thereby changing thevertical location of the abutment 185 the extent of movement of thelpiston .19, stem 16' and "valve head 'l'llmayrbe, varied so that a greater or less time will be required for the automatic" valve to, close. A feature of importance is that after such an adjustment islmade every'time the valvel3 is opened for joltingrpurposes'identically the same number of jolts will beapplied, there- 7 by insuring uniformity. in the packing v of "the sand about'the patterns. 1 7 V After thejolting operation isoompleted'the valve handle 40 should of course be returnedto its'neutral or intermediate position to close the V supply port whereupon the pressure off the 'spring- 8!) willforce the piston 19, 'stem'lfi and valvewhead 11 downwardly- .soethat thefioutlet; 7 port 14 will again be unobstructed, the partsbe- 601 ing then ready, for the next desiredjolting operation. Wh'en the piston'a'nd :associatedfparts thus; moves downwardly, {suction is produced in :the a 'ichamber 39 whereupon 'oil will'be'drawn from 'theireservoirrfifi thiiough'the port 90 and passage f 9|, unseatingithe ball 92 and againfilling'the' chamber 89. w

After the jolting operation, the manual valve; 23' is opened by swinging the handle lily-130 the squeezeposition, whereupon fair i's admitted through the pipe 34 into the large squeeze=cylinder Ztoraise the piston l. The piston Wear- ,ries upwardly with it the plunger IBVQth'ehead H, the flask'supporting frame 59, the flask -58 and the pattern plate until the Dresser-board '94 is forced against the pressure head to compress the sand about the patterns. When the valve handle- 40 is thus -moved, the automatic latch 43 engaging behind the shoulder'50,=as previously 7 described, will prevent manual movement of 'the valve to its exhausting position until the pres sure'within'the" squeeze cylinder has reachedthe maximum, whereupon the air pressure'in the squeeze cylinder passing through the. port 53 'and' pipe 52 into'the chamber 42 beneath the piston 44 will release the latch and permit the operator to move the valve into its exhaust positionso that the air pressure inthe squeeze cylinder-2 may pass-backrthroughfthe pipe 34 back tothe' valve body or casing'25 and outthrough the exh'aust port to the atmosphere. 7

,From the foregoingdescription and a study or the drawings'itw'ill'be apparent that' therehas thus been provided'a molding machine having;

premature .release of the. squeeze 'rmechanism,

positive and efficientmeansfor' governing auto matioally, the number of jolts and for preventing" thereby insuring uniform packing and density'of the sand about the pattern. 7 The mechanism is simple and'may be applie'd'to already existing mold machines of the typedisclosed andevenjot difierent varietiesias there is no, definite limita-' tion in this respect. It isthought from thegabove thatthe. construction, operation and advantages will belreadily apparent to one skilled in'theart without further explanation. ,7

'While there has been shownand be understood that the disclosure is merelyian exemplification .of the'principlesyinvolved as thej right is reserved to make allisuoh chan'gjsin the described the 1 preferred-embodiment of theinyention, itshould details of constructionasrwillwiden the field of. 1 utility .and increasetheadaptability of the d evice provided such changes-'constitutelno depar ture from the spirit of the invention or the scope of theclaims hereunto appended; V l

Having thus described the invention, we

clairn z.

1...In a molding ma'chineQthe combination ofia squeeze cylinder and a pistonoperating therein, a jolting cylinder, a jolting plunger operatingwithe in the jolting cylinder, and supporting means for a flaskfto'berjolted byQsaid jolting plunger and subsequently pressed by. said squeeze piston, a manually v operable control-valve for selectivelv supplying fluidpressure to the joltingplunger or to the squeeze cylinder and for subsequentlyexhausting fluid pressure from (the latter, .vmeans for-preventing operation ofthe valve to .exhaustf fluid pressureirom the squeeze. cylinderuntil the pressuretherein ha's reached the maximum; and

a normally open and retardedly closed automatic fiuidpressure operated valve ren ote and separate. I

hausting fluid pressure from the'latter,---means mally open and retarde'dly' closed automatic fluid v 'supplyinglfluid pressureto the .jolting plunger or I tothesqueeze cylinder andfor subsequently ex 'i- 'Jrpreventing operation of theWalVe'to-eXhaust fiuidpressurdfromthe squeeze cylinderuntil the pressure therein has rea'ched t'he maximumm'nor V pressure operated valve interposed between the fluid pressure connection from the manual valve to said jolting cylinder, and means for adjusting said automatic valve for varying the duration of the flow of fluid pressure therethrough and thereby controlling the number of impacts of the jolting plunger imparted to the flask support.

3. A molding machine comprising, combination, a squeeze cylinder having a squeeze piston therein, a jolting cylinder within the squeeze pis ton, a jolting plunger within the jolting cylinder. a support for a flask above both of said cylinders to be repeatedly jolted and then squeezed, dii ferential ported communication between the jolting cylinder and the atmosphere for efiecting reciprocation of the jolting plunger as long as the fluid pressure is supplied within the jolting cylinder, a manual control valve selectively operable to supply fluid pressure to the jolting cylinder, to the squeeze cylinder or to exhaust fluid pressure from the latter to the atmosphere, an automatic valve interposed in the fluid pressure connection between said manual valve and the jolting cylinder for varying the duration of the flow of fluid pressure to the latter and means for automatically locking said manual control valve in squeeze cylinder operating position until the pressure therein has reached a maximum.

4. A molding machine comprising, in combination, a squeeze cylinder having a squeeze piston therein, a jolting cylinder within the squeeze piston, a jolting plunger within the jolting cylinder. a support for a flask above both of said cylinders to be repeatedly jolted and then squeezed, differential ported communication between the jolting cylinder and the atmosphere for effecting reciprocation of the jolting plunger as long as the fluid pressure is supplied within the jolting cylinder, a manual control valve selectively operable to supply fluid pressure to the jolting cylinder, to the squeeze cylinder or to exhaust fluid pressure from the latter to the atmosphere, an automatic valve interposed in the fluid pressure connection between said manual valve and the jolting cylinder for varying the duration of the flow of fluid pressure to the latter, said automatic valve having an inlet and an outlet, a longitudinally movable valve head within the automatic valve normally in non-obstructing relation to the outlet therefrom, means responsive to fluid pressure entering the inlet for moving said valve head to outlet closing position and means for automatically locking said manual control Valve in squeeze cylinder operating position until said squeeze cylinder pressure has attained a maximum.

5. A molding machine comprising, in combination, a squeeze cylinder having a squeeze piston therein, a jolting cylinder within the squeeze piston, a jolting plunger within the jolting cylinder, a support for a flask above both of said cylinders to be repeatedly jolted and then squeezed, differential ported communication between the jolting cylinder and the atmosphere for efiecting reciprocation of the jolting plunger as long as the fluid pressure is supplied within the jolting cylinder, a manual control valve selectively operable to supply fluid pressure to the jolting cylinder, to the squeeze cylinder or to exhaust fluid pressure from the latter to the atmosphere, an automatic valve interposed in the fluid pressure connection between said manual valve and the jolting cylinder for varying the duration of the flow of fluid pressure to the latter, said automatic valve having an inlet and an outlet, a longitudinally movable valve head within the automatic valve normally in non-obstructing relation to the outlet therefrom, means responsive to fluid pressure entering the inlet for moving said valve head to outlet closing position, means opposing movement of said valve head and thereby retarding closing of said outlet and means for automatically locking said manual control valve in squeeze cylinder operating position until said squeeze cylinder pressure has attained a maximum.

6. A molding machine comprising, in combination, a squeeze cylinder having a squeeze piston therein, a iolting cylinder within the squeeze piston, a jolting plunger within the jolting cylinder, a support for a flask above both of said cylinders to be repeatedly jolted and then squeezed, differential ported communication between he jolting cylinder and the atmosphere for efiecting reciprocation of the ,iolting plunger as long as the fluid pressure is supplied Within the jolting cylinder, a manual control valve selectively operable to supply fluid pressure to the jolting cylinder, to the squeeze cylinder or to exhaust fluid pressure from the latter to the atmosphere, a fully automatic valve interposed in the fluid pressure connection between said manual valve and the jolting cylinder for varying the duration of the flow of fluid pressure to the latter, said automatic valve comprising a casing having an inlet and an outlet, a longitudinally movable stem within said casing carrying a head normally in non-obstructing relation to the outlet but adapted to close the same, said head having passages to permit fluid pressure entering the casing to pass through the head, a piston on the stem adapted to be moved by fluid pressure passing through the head, circulatory fluid means in advance of said last named piston for opposing movement thereof and thereby retarding closing movement or" said valve head, fluid pressure means for locking said manual control valve in squeeze cylinder operating position, and means for releasing said locking means after said squeeze cylinder pressure has attained a maximum.

7. In a molding machine, a jolting mechanism comprising a vertically disposed cylinder; a plunger in said cylinder; a mold flask support adapted to be raised and lowered by the reciprocation of the plunger; a compressed air reservoir carried by the plunger and provided with a charging port to receive air from a compressor; an admission port leading from the reservoir to the cylinder below the plunger, an exhaust port leading from the cylinder adjacent the lower end thereof; the plunger being adapted to close the exhaust port in its lowermost position and to open said port when it raises to a certain height, a manual valve for supplying fluid pressure to the cylinder, an automatic valve interposed between the manual valve and said cylinder, said automatic valve being operated entirely by fluid pressure supplied thereto by said manual valve but being separate therefrom, and embodying means for cutting off passage of fluid pressure to the cylinder after a predetermined length of time, fluid pressure means for locking said manual control valve in squeeze cylinder operating position, and means for releasing said locking means after said squeeze cylinder pressure has attained a maximum.

8. In a molding machine, a jolting mechanism comprising a vertically disposed cylinder; a plunger in said cylinder; a mold flask support adapted to be raised and lowered by the reciprocation of :rtnezplunger:'and;provided with a; charging portto receiveair from a compressor; an admission iport leadin'gifrom the reservoir? to the. cylinder below the: plunger, an exhaustpOrt leading from the :cylinderadjacent the lower end thereof; the "plunger being adaptedltowclose the exhaust port int itsl lowermost; position and to open said port 7 it raises to a, certain heightga'. manually operable valve for supplying fluid pressure to said cylinder; and an automatic valveinterposedin the fluid pressure connection between the manual valve andsaid cylinder; said automatic valve comprising a casing having'an inlet and an outlet, a. single stem: slidable -axially of said casin an a V '2,-102 377 V theplungemacompressed air reservoirvcarried'rby- V 'aperturediheadon' said v stem normallye in nonobstructing, relation. to said outlet. but: movable Q 130101086: the: same, a piston lcarriedflby, saidz; stem subiected'. to fluid pressure enterin'gqthe inlet and passing; through said. apertured 'head',1hy.-

drau-lic-zmeans preventing rapid :movementlotsaid last named-piston and thereby retarding the'closl ing.;movement of said valve head, fluidpressure V meansv for: lockingisaid manual control valvelnv squeeze cylinder operating position, and; means for releasing 'saidilocking means after'saidlsqueene 7 cylinder pressure has attalned'a maximum H. mums. GUSTAVE ANDERSON; 

